Joint Physiology Flashcards
what are the 3 main types of joint in the body
synovial
fibrous
cartilaginous
what are fibrous joints
bones united by fibrous tissue
doesn’t allow movement
example: skull bones
what are cartilaginous joints
bones united by cartilage
allow limited movement
example: intervertebral discs, pubic symphysis
what are synovial joints
bones separated by a cavity (containing synovial fluid)
united by a fibrous capsule
what is the inside of the fibrous capsule in the synovial joint lines with
synovial membrane
what is the synovial membrane
vascular connective tissue with capillary networks and lymphatics
what do synovial cells produce and where are they found
synovial fluid
found in the synovial membrane
what is a simple synovial joint
joint with one pair of articulating surfaces
what is a compound synovial joint
more than one pair of articulating surfaces eg. elbow
what is the role of joints during purposeful motion
stress distribution
confer stability
what are the functions of synovial fluid
lubricated joint
facilitates joint movement- reduces friction
minimises wear and tear
Aids nutrition of articular cartilage
supplies chondrocytes with O2 and removes CO2 and waste products
the synovial fluid is a static pool true/false
false
it is continuously replenished and absorbed by the synovial membrane
what gives synovial fluid its high viscosity
the presence of hyaluronic acid (mucin) produced by synovial cells
where are the other constituents of synovial fluid derived from
dialysis of blood plasma
how does rapid movement change viscosity and elasticity of synovial fluid
decreased viscosity
increased elasticity
(this doesn’t work in diseased joints eg. osteoarthritis)
what does normal synovial fluid look like
clear and colourless liquid
the synovial fluid WBC count increases/decreases in inflammatory and septic arthritis
increases
when does the synovial fluid turn red
in traumatic synovial tap and haemorrhage arthritis
what does synovial fluid from a severely inflamed joint look like
thin and opaque
what are the main functions of articular cartilage
prevents wear and tear
distributes the contact pressure to subchondral bone
what zones make up articular cartilage
superficial, middle, deep, calcified
what type of cartilage is the articular cartilage
usually hyaline
it is elastic with sponge-like qualities
what is the articular cartilage ECM made up of
predominantly water (70%) 20% collagen (mainly type 2) proteoglycans (10%)
what happens to cartilage water content with age
decreases with age
what do the proteoglycans do
responsible for compressive properties associated with weight baring
what cells synthesise, organise and degrade the cartilage ECM
chondrocytes
how do the articular cartilage cells get nutrients and O2
via the synovial fluid as they are avascular
what happens when there is a change in the amounts of the 3 major components of cartilage (water, collagen and proteoglycans)
the mechanical properties of cartilage would change and joint disease would occur is the rate of ECM degeneration exceeds the rate of its synthesis
what are catabolic factors in cartilage matrix turnover
segregation of the cartilage matrix
proteolytic enzymes are stimulated and proteoglycan synthesis is inhibited
what do anabolic facts in cartilage matrix turnover do
stimulate proteoglycan syntehsis and contract the effects of IL1 (a catabolic factor)
what are two markers of cartilage degradation
serum and synovial keratin sulphate (increased levels)
increased levels of type 2 collagen (Indicated cartilage breakdown)
what is osteoarthritis
when cartilage and synovial composition and function deteriorate with age/ wear and tear
what happens in rheumatoid arthritis
synovial cell proliferation and inflammation
what happens when there are uric acid crystals in the joints
gouty arthritis
what is soft tissue rheumatism
injury and inflammation to periarticular structures
